Honor includes in partial_dependency of externals dependencies

docs/markdown/snippets/preserve_include_in_partial_dependencies.md

@@ -0,0 +1,9 @@
+## partial_dependency now honor includes keyword for external dependencies.
+
+Previously, the `includes` keyword of [[@dep]]`.partial_dependency` had no effects
+if the dependency was an external dependency (e.g. from [[dependency]]).
+
+Since 1.8.0, specifying `includes: true` will now extract the include directories
+from the compile args, when `compile_args` is `false`. 
+However, to preserve backward compatibility, `includes: false` will not remove the
+include dirs from the compile args when `compile_args` is `true`.

docs/yaml/objects/dep.yaml

@@ -138,6 +138,9 @@ methods:
       - includes: any include_directories
       - sources: any compiled or static sources the dependency has
 
+      *(since 1.8.0)* If `includes` is `true`, `-I` compile args will be preserved
+                      for external dependencies, even if `compile_args` is `false`.
+
     warnings:
       - A bug present until 0.50.1 results in the above behavior
         not working correctly.

mesonbuild/dependencies/base.py

@@ -420,13 +420,14 @@ def get_partial_dependency(self, *, compile_args: bool = False,
         new = copy.copy(self)
         new._id = uuid.uuid4().int
         if not compile_args:
-            new.compile_args = []
+            if includes:
+                new.compile_args = [c for c in self.compile_args if c.startswith('-I')]
+            else:
+                new.compile_args = []
         if not link_args:
             new.link_args = []
         if not sources:
             new.sources = []
-        if not includes:
-            pass # TODO maybe filter compile_args?
         if not sources:
             new.sources = []
 

test cases/common/183 partial dependency/external_dependency/meson.build

@@ -1,8 +1,7 @@
 # SPDX-License-Identifier: Apache-2.0
 # Copyright © 2024 Intel Corporation
 
-# TODO: don't use compile whenever we get includes and compile args separated
-dep_zlib_sub = dep_zlib.partial_dependency(compile_args : true, includes : true)
+dep_zlib_sub = dep_zlib.partial_dependency(includes : true)
 
 executable(
   'zlib header only test',

test cases/frameworks/1 boost/partial_dep/meson.build

@@ -13,7 +13,7 @@
 # limitations under the License.
 
 dep_boost = dependency('boost')
-dep_boost_headers = dep_boost.partial_dependency(compile_args : true)
+dep_boost_headers = dep_boost.partial_dependency(includes : true)
 
 libfoo = static_library(
   'foo',